Relation of echocardiographic left ventricular mass, geometry and wall stress, and left atrial dimension to coronary calcium in young adults (the CARDIA study)

Association of left ventricular diastolic function with coronary artery calcium score: A Project Baseline Health Study

BACKGROUND

Coronary artery calcium (CAC) and left ventricular diastolic dysfunction (LVDD) are strong predictors of cardiovascular events and share common risk factors. However, their independent association remains unclear.

METHODS

In the Project Baseline Health Study (PBHS), 2082 participants underwent cardiac-gated, non-contrast chest computed tomography (CT) and echocardiography. The association between left ventricular (LV) diastolic function and CAC was assessed using multidimensional network and multivariable-adjusted regression analyses. Multivariable analysis was conducted on continuous LV diastolic parameters and categorical classification of LVDD and adjusted for traditional cardiometabolic risk factors. LVDD was defined using reference limits from a low-risk reference group without established cardiovascular disease, cardiovascular risk factors or evidence of CAC, (n ​= ​560). We also classified LVDD using the American Society of Echocardiography recommendations.

RESULTS

The mean age of the participants was 51 ​± ​17 years with 56.6% female and 62.6% non-Hispanic White. Overall, 38.1% had hypertension; 13.7% had diabetes; and 39.9% had CAC >0. An intertwined network was observed between diastolic parameters, CAC score, age, LV mass index, and pulse pressure. In the multivariable-adjusted analysis, e', E/e', and LV mass index were independently associated with CAC after adjustment for traditional risk factors. For both e' and E/e', the effect size and statistical significance were higher across increasing CAC tertiles. Other independent correlates of e' and E/e' included age, female sex, Black race, height, weight, pulse pressure, hemoglobin A1C, and HDL cholesterol. The independent association with CAC was confirmed using categorical analysis of LVDD, which occurred in 554 participants (26.6%) using population-derived thresholds.

CONCLUSION

In the PBHS study, the subclinical coronary atherosclerotic disease burden detected using CAC scoring was independently associated with diastolic function.

CLINICALTRIALS

GOV IDENTIFIER

NCT03154346.

Echocardiographic parameters of left ventricular structure and diastolic function and their relation to coronary artery calcification

Alteration in left ventricular (LV) structure and diastolic function is associated with poor cardiovascular (CV) prognosis. Coronary artery calcium score (CACS) is a reliable marker for coronary artery calcification, predicting adverse CV events. However, evidence is still insufficient to establish the association between alteration in LV structure and diastolic function and CACS. 9053 Korean adults (male: 84.2%, mean age: 42.5 years) were grouped by quartile levels of echocardiographic parameters for LV structure and diastolic function. CACS was detected by multidirectional computed tomography and categorized into CACS > 0 or CACS = 0. Multivariate regression analysis was used to calculate adjusted odd ratios (OR) and 95% confidence interval (CI) for CACS > 0 (adjusted OR [95% CI]) in each quartile group of echocardiographic parameters (reference: quartile 1 group). CACS > 0 was significantly associated with structural parameters above third quartile in LVMI (1.19 [1.00-1.41]), RWT (1.23 [1.03-1.46]) and IVST (1.42 [1.20-1.70]) and fourth quartile in PWT (1.36 [1.14-1.63]). In parameters of diastolic function, septal e' velocity ≥ 10.7 cm/s (fourth quartile) was less associated with CACS > 0 than septal e' velocity ≤ 7.7 cm/s (first quartile). Additionally, the fourth quartile of E/e' was more significantly associated with CACS > 0 than that of first quartile. Echocardiographic parameters close to LV hypertrophy and LV diastolic dysfunction are associated with CACS > 0.

Association of subclinical atherosclerosis with echocardiographic indices of cardiac remodeling: The Framingham Study

Background

It is well established that coronary artery disease progresses along with myocardial disease. However, data on the association between coronary artery calcium (CAC) and echocardiographic variables are lacking.

Methods and results

Among 2,650 Framingham Study participants (mean age 51 yrs, 48% women; 40% with CAC>0), we related CT-based CAC score to left ventricular (LV) mass index (LVMi), LV ejection fraction (LVEF), E/e’, global longitudinal strain (GLS), left atrial emptying fraction (LAEF), and aortic root diameter (AoR), using multivariable-adjusted generalized linear models. CAC score (independent variable) was used as log-transformed continuous [ln(CAC+1)] and as a categorical (0, 1–100, and ≥101) variable. Adjusting for standard risk factors, higher CAC score was associated with higher LVMi and AoR (β_LVMI per 1-SD increase 0.012, β_AoR 0.008; P<0.05, for both). Participants with 1≤CAC≤100 and those with CAC≥101 had higher AoR (β_AoR 0.013 and 0.020, respectively, P = 0.01) than those with CAC = 0. CAC score was not significantly associated with LVEF, E/e’, GLS or LAEF. Age modified the association of CAC score with AoR; higher CAC scores were associated with larger AoR more strongly in older (>58 years; β_AoR0.0042;P<0.007) than in younger (≤58 years) participants (β_AoR0.0027;P<0.03).

Conclusions

We observed that subclinical atherosclerosis was associated with ventricular and aortic remodeling. The prognostic significance of these associations warrants evaluation in additional mechanistic studies.

Coronary Artery Calcium From Early Adulthood to Middle Age and Left Ventricular Structure and Function

Background The relationship of coronary artery calcium (CAC) with adverse cardiac remodeling is not well established. We aimed to study the association of CAC in middle age and change in CAC from early adulthood to middle age with left ventricular (LV) function. Methods CAC score was measured by computed tomography at CARDIA study (Coronary Artery Risk Development in Young Adults) year-15 examination and at year-25 examination (Y25) in 3043 and 3189 participants, respectively. CAC score was assessed as a continuous variable and log-transformed to account for nonlinearity. Change in CAC from year-15 examination to Y25 was evaluated as the absolute difference of log-transformed CAC from year-15 examination to Y25. LV structure and function were evaluated by echocardiography at Y25. Results At Y25, mean age was 50.1±3.6 years, 56.6% women, 52.4% black. In the multivariable analysis at Y25, higher CAC was related to higher LV mass (β=1.218; adjusted P=0.007), higher LV end-diastolic volume (β=0.811; adjusted P=0.007), higher LV end-systolic volume (β=0.350; adjusted P=0.048), higher left atrial volume (β=0.214; adjusted P=0.009), and higher E/e' ratio (β=0.059; adjusted P=0.014). CAC was measured at both year-15 examination and Y25 in 2449 individuals. Higher change in CAC score during follow-up was independently related to higher LV mass index in blacks (β=4.789; adjusted P<0.001), but not in whites (β=1.051; adjusted P=0.283). Conclusions Higher CAC in middle age is associated with higher LV mass and volumes and worse LV diastolic function. Being free of CAC from young adulthood to middle age correlates to better LV function at middle age. Higher change in CAC score during follow-up is independently related to higher LV mass index in blacks.

Predominant location of coronary artery atherosclerosis in the left anterior descending artery. The impact of septal perforators and the myocardial bridging effect

Introduction

Coronary artery atherosclerosis presents characteristic patterns of plaque distribution despite systemic exposure to risk factors. We hypothesized that local hemodynamic forces induced by the systolic compression of intramuscular septal perforators could be involved in atherosclerotic processes in the left anterior descending artery (LAD) adjacent to the septal perforators’ origin. Therefore we studied the spatial distribution of atherosclerosis in coronary arteries, especially in relation to the septal perforators’ origin.

Material and methods

64-slice computed tomography angiography was performed in 309 consecutive patients (92 male and 217 female) with a mean age of 59.9 years. Spatial plaque distribution in the LAD was analyzed in relation to the septal perforators’ origin. Additionally, plaque distribution throughout the coronary artery tree is discussed.

Results

The coronary calcium score (CCS) was positive in 164 patients (53.1%). In subjects with a CCS > 0, calcifications were more frequent in the LAD (n = 150, 91.5%) compared with the right coronary artery (RCA) (n = 94, 57.3%), circumflex branch (CX) (n = 76, 46.3%) or the left main stem (n = 42, 25.6%) (p < 0.001). Total CCS was higher in the LAD at 46.1 (IQR: 104.2) and RCA at 34.1 (IQR: 90.7) than in the CX at 16.8 (IQR: 61.3) (p = 0.007). In patients with calcifications restricted to a single vessel (n = 54), the most frequently affected artery was the LAD (n = 42, 77.8%). In patients with lesions limited to the LAD, the plaque was located mostly (n = 37, 88.1%) adjacent to the septal perforators’ origin.

Conclusions

We demonstrated that coronary calcifications are most frequently located in the LAD in proximity to the septal branch origin. A possible explanation for this phenomenon could be the dynamic compression of the tunneled septal branches, which may result in disturbed blood flow in the adjacent LAD segment (milking effect).

The role of septal perforators and "myocardial bridging effect" in atherosclerotic plaque distribution in the coronary artery disease

The distribution of atherosclerotic plaque burden in the human coronary arteries is not uniform. Plaques are located mostly in the left anterior descending artery (LAD), then in the right coronary artery (RCA), circumflex branch (LCx) and the left main coronary artery (LM) in a decreasing order of frequency. In the LAD and LCx, plaques tend to cluster within the proximal segment, while in the RCA their distribution is more uniform. Several factors have been involved in this phenomenon, particularly flow patterns in the left and right coronary artery. Nevertheless, it does not explain the difference in lesion frequency between the LAD and the LCx as these are both parts of the left coronary artery. Branching points are considered to be the risk points of atherosclerosis. In the LCx, the number of side branches is lower than in the LAD or RCA and there are no septal perforators with intramuscular courses like in the proximal third of the LAD and the posterior descending artery (PDA). We hypothesized that septal branches generate disturbed flow in the LAD and PDA in a similar fashion to the myocardial bridge (myocardial bridging effect). This coronary architecture determines the non-uniform plaque distribution in coronary arteries and LAD predisposition to plaque formation.

Left atrial dimension and traditional cardiovascular risk factors predict 20-year clinical cardiovascular events in young healthy adults: the CARDIA study

AIMS

We investigated whether the addition of left atrial (LA) size determined by echocardiography improves cardiovascular risk prediction in young adults over and above the clinically established Framingham 10-year global CV risk score (FRS).

METHODS AND RESULTS

We included white and black CARDIA participants who had echocardiograms in Year-5 examination (1990-91). The combined endpoint after 20 years was incident fatal or non-fatal cardiovascular disease: myocardial infarction, heart failure, cerebrovascular disease, peripheral artery disease, and atrial fibrillation/flutter. Echocardiography-derived M-mode LA diameter (LAD; n = 4082; 149 events) and 2D four-chamber LA area (LAA; n = 2412; 77 events) were then indexed by height or body surface area (BSA). We used Cox regression, areas under the receiver operating characteristic curves (AUC), and net reclassification improvement (NRI) to assess the prediction power of LA size when added to calculated FRS or FRS covariates. The LAD and LAA cohorts had similar characteristics; mean LAD/height was 2.1 ± 0.3 mm/m and LAA/height 9.3 ± 2.0 mm(2)/m. After indexing by height and adjusting for FRS covariates, hazard ratios were 1.31 (95% CI 1.12, 1.60) and 1.43 (95% CI 1.13, 1.80) for LAD and LAA, respectively; AUC was 0.77 for LAD and 0.78 for LAA. When LAD and LAA were indexed to BSA, the results were similar but slightly inferior. Both LAD and LAA showed modest reclassification ability, with non-significant NRIs.

CONCLUSION

LA size measurements independently predict clinical outcomes. However, it only improves discrimination over clinical parameters modestly without altering risk classification. Indexing LA size by height is at least as robust as by BSA. Further research is needed to assess subgroups of young adults who may benefit from LA size information in risk stratification.

Association of early adult modifiable cardiovascular risk factors with left atrial size over a 20-year follow-up period: the CARDIA study

OBJECTIVES

We investigate how early adult and 20-year changes in modifiable cardiovascular risk factors (MRF) predict left atrial dimension (LAD) at age 43-55 years.

METHODS

The Coronary Artery Risk Development in Young Adults (CARDIA) study enrolled black and white adults (1985-1986). We included 2903 participants with echocardiography and MRF assessment in follow-up years 5 and 25. At years 5 and 25, LAD was assessed by M-mode echocardiography, then indexed to body surface area (BSA) or height. Blood pressure (BP), body mass index (BMI), heart rate (HR), smoking, alcohol use, diabetes and physical activity were defined as MRF. Associations of MRF with LAD were assessed using multivariable regression adjusted for age, ethnicity, gender and year-5 left atrial (LA) size.

RESULTS

The participants were 30±4 years; 55% white; 44% men. LAD and LAD/height were modest but significantly higher over the follow-up period, but LAD/BSA decreased slightly. Increased baseline and 20-year changes in BP were related to enlargement of LAD and indices. Higher baseline and changes in BMI were also related to higher LAD and LAD/height, but the opposite direction was found for LAD/BSA. Increase in baseline HR was related to lower LAD but not LAD indices, when only baseline covariates were included in the model. However, baseline and 20-year changes in HR were significantly associated to LA size.

CONCLUSIONS

In a biracial cohort of young adults, the most robust predictors for LA enlargement over a 20-year follow-up period were higher BP and BMI. However, an inverse direction was found for the relationship between BMI and LAD/BSA. HR showed an inverse relation to LA size.

Infant macronutrient composition is associated with differences in cardiovascular structures and function in childhood

Early-life nutrition may influence cardiovascular development. Not much is known about the associations between dietary composition and cardiovascular risk factors in childhood. We examined the associations of infant macronutrient intake with cardiovascular structures and function in 2882 children participating in a prospective, population-based cohort study. Information on macronutrient intake at the age of 14 mo was obtained from food-frequency questionnaires completed by a parent. Systolic and diastolic blood pressure, carotid-femoral pulse wave velocity (PWV), fractional shortening, and left cardiac structures (left atrial diameter, aortic root diameter, and left ventricular mass) were measured at the age of 6 y. Linear regression analyses were performed by using energy-adjusted macronutrient intakes, adjusted for maternal, child, and other dietary factors. Higher total fat intake was associated with higher carotid-femoral PWV (P-trend = 0.03), whereas higher intakes of total carbohydrate and mono- and disaccharides were associated with lower carotid-femoral PWV. No consistent associations were observed for macronutrient intake with systolic blood pressure, diastolic blood pressure, fractional shortening, and aortic root diameter. Higher intakes of total, saturated, monounsaturated, and polyunsaturated fat were associated with lower left atrial diameter (all P-trend ≤ 0.01), and higher total carbohydrate and mono- and disaccharide intakes were associated with higher left atrial diameter (P-trend < 0.01 and 0.02, respectively). Furthermore, the third tertile of mono- and disaccharide intake was associated with a higher left ventricular mass (difference: 1.01 g; 95% CI: 0.18, 1.85 g; P = 0.02). Dietary macronutrient composition in infancy may lead to developmental differences in cardiovascular structures and function in childhood. Further studies are needed to investigate whether these differences have consequences for the risk of future cardiovascular disease.

Family history of cardiovascular disease and offspring echocardiographic left ventricular structure and function: the Asklepios Study

BACKGROUND

Moderate to small heritability has been observed for left ventricular (LV) structure and function in genetic epidemiology and genomewide association studies. The aim of this study was to explore whether this would be mirrored in an independent association between LV structure and function and a family history (FH) of cardiovascular disease (CVD) in a large population of middle-aged adults.

METHODS

Subjects enrolled in the Asklepios Study, a population-based sample of 2,524 male and female volunteers, aged 35 to 55 years, free of overt CVD at baseline, were studied. LV structure and function were assessed using transthoracic echocardiography (by a single sonographer). FH data spanning 4 generations were acquired using a questionnaire.

RESULTS

In unadjusted analyses, only small effects of FH of CVD on LV structure (relative wall thickness, P = .042; interventricular septal thickness, P = .002; LV mass, P = .038; allometrically adjusted LV mass, P = .014) and diastolic function (mitral annular e', P = .02) were observed. After adjusting for the more adverse risk factor profile associated with FH, no significant associations persisted. These results did not appreciably change using a more extended definition of FH of CVD or FH of hypertension.

CONCLUSIONS

A positive FH for CVD was associated with differences in offspring cardiac structure and function, largely mediated by (but not independent from) a more adverse risk profile in those subjects with positive FH.

Nonobstructive coronary artery disease as detected by 64-detector row cardiac computed tomographic angiography is associated with increased left ventricular mass

BACKGROUND

Cardiac computed tomographic angiography (CCTA) permits simultaneous assessment of coronary artery disease (CAD) and left ventricular mass (LVM). While increased LVM predicts mortality and is associated with obstructive CAD, the relationship of LVM with non-obstructive CAD is unknown.

METHODS

We evaluated 212 consecutive patients undergoing 64-detector row CCTA at 2 sites without evident cardiovascular disease or obstructive (≥70%) CAD by CCTA. LVM was measured by CCTA using Simpson's method of disks and indexed to body surface area (LVMI) and height to the allometric power of 2.7(LVM/ht2.7). CCTAs were evaluated by scoring a modified AHA 16-segment coronary artery model for none = 0 (0% stenosis), mild = 1 (1-49% stenosis) or moderate = 2 (50-69% stenosis). Overall CAD plaque burden was estimated by summing scores across all segments for a segment stenosis score (SSS, max = 32).

RESULTS

The mean age was 53.3 ± 12.8 with 52% female, 48% hypertensive, and 7.4% diabetic. The mean LVM was 109 ± 32.5 g; 58.5% had any coronary artery plaque. In multivariable linear regression, SSS was significantly associated with increased LVM, LVMI and LVM/ht2.7. LVM increased by 2.0 g for every 1-point increase in SSS (95% CI 0.06-3.4, p = 0.006). Agatston scores provided no additional predictive value for increased LVM above and beyond SSS.

CONCLUSION

Non-obstructive CAD visualized by CCTA is associated with increased LVM independent of effects of clinical risk factors and calcium scoring. Whether addition of LVM to stenosis assessment in patients undergoing CCTA enhances risk prediction of future CAD events warrants investigation.

Left atrial volume and index by multi-detector computed tomography: comprehensive analysis from predictors of enlargement to predictive value for acute coronary syndrome (ROMICAT study)

OBJECTIVES

We aimed to identify the predictors of left atrial (LA) enlargement by multi-detector computed tomography (CT) and determine its association and predictive value for acute coronary syndrome (ACS).

BACKGROUND

LA enlargement is associated with myocardial ischemia and coronary artery disease (CAD) and is a strong predictor for cardiovascular events. These studies were performed primarily with echocardiography. With the rise of cardiac CT, LA volume can be readily measured.

METHODS

In 377 emergency department patients with chest pain, we performed 64-slice CT for coronary artery assessment. We derived LA volumes (LAV(max), LAV(min)) and indices (LAVI(max), LAVI(min)) using a threshold-based volumetric method.

RESULTS

Subjects, with cardiac risk factors or CAD by CT, had larger LA (ΔLAV(max) 9.1 ml, p=0.004; ΔLAV(min) 8.1 ml, p=0.001; ΔLAVI(max) 3.3 ml/m(2), p=0.03; ΔLAVI(min) 3.4 ml/m(2), p=0.006) than controls. Predictors of LA enlargement were related to risk factors for diastolic dysfunction. ACS risk was greater in patients with top quartile LAV(max) (odds ratio [OR] 3.4, p=0.02) and LAV(min) (OR 4.7, p=0.01) than lowest quartile, but not when indexed. Similarly, the predictive values of LA volumes were incrementally better when added to CT finding of indeterminate stenosis (LAV(max): C statistic 0.62 to 0.70, p=0.046; LAV(min): C statistic 0.65 to 0.73, p=0.008), but not when indexed.

CONCLUSIONS

Risk factors related to diastolic dysfunction are independent predictors of LA enlargement. LA enlargement by volumes are associated with a 3-5 fold increase risk for ACS and have incremental value for predicting ACS when added to the CT finding of indeterminate stenosis.

Association of cardiomegaly with coronary artery histopathology and its relationship to atheroma

AIMS

Hypertrophied hearts at autopsy often display excessive coronary artery atherosclerosis, but the histopathology of coronary arteries in hearts with and without cardiomegaly has rarely been compared.

METHODS

In this study, forensic autopsies provided hearts with unexplained enlargement plus comparison specimens. Right coronary artery was opened longitudinally and flattened for formalin fixation and H&E-stained paraffin sections were cut perpendicular to the endothelial surface. The micro-scopically observed presence or absence of a necrotic atheroma in the specimen was recorded. At multiple sites far removed from any form of atherosclerosis, measurements were taken of intimal thickness, numbers of smooth muscle cells (SMC) and their ratio, the thickness per SMC, averaged over the entire nonatheromatous arterial length. When the mean thickness per SMC exceeded a certain cutoff point, the artery was declared likely to contain a necrotic atheroma.

RESULTS

The prevalence of specimens with necrotic atheromas increased stepwise with increasing heart weight, equally with fatal or with incidental cardiomegaly, and equally with hypertension- or obesity-related hypertrophy, rejecting further inclusion of appreciable age, race, or gender effects. The prevalence of specimens with thickness per SMC exceeding the cutoff point was almost always nearly identical to the prevalence of observed necrotic atheroma, showing the two variables to be tightly linked to each other with quantitative consistency across group comparisons of every form.

CONCLUSIONS

In summary, cardiomegaly, irrespective of the specific cause, seems to accelerate the risk of atheromas, and to do so by first altering the arterial architecture, especially by increasing intimal thickness per SMC.

Statistical modeling of Agatston score in multi-ethnic study of atherosclerosis (MESA)

The MESA (Multi-Ethnic Study of Atherosclerosis) is an ongoing study of the prevalence, risk factors, and progression of subclinical cardiovascular disease in a multi-ethnic cohort. It provides a valuable opportunity to examine the development and progression of CAC (coronary artery calcium), which is an important risk factor for the development of coronary heart disease. In MESA, about half of the CAC scores are zero and the rest are continuously distributed. Such data has been referred to as “zero-inflated data” and may be described using two-part models. Existing two-part model studies have limitations in that they usually consider parametric models only, make the assumption of known forms of the covariate effects, and focus only on the estimation property of the models. In this article, we investigate statistical modeling of CAC in MESA. Building on existing studies, we focus on two-part models. We investigate both parametric and semiparametric, and both proportional and nonproportional models. For various models, we study their estimation as well as prediction properties. We show that, to fully describe the relationship between covariates and CAC development, the semiparametric model with nonproportional covariate effects is needed. In contrast, for the purpose of prediction, the parametric model with proportional covariate effects is sufficient. This study provides a statistical basis for describing the behaviors of CAC and insights into its biological mechanisms.

Relation of left ventricular mass and concentric remodeling to extent of coronary artery disease by computed tomography in patients without left ventricular hypertrophy: ROMICAT study

OBJECTIVE

Cardiac computed tomography allows for simultaneous assessment of left ventricular mass (LVM) and coronary artery disease (CAD). We aimed to determine whether LVM, LVM index (LVMi), and the left ventricular geometric pattern of concentric remodeling are associated with the extent of CAD in patients without left ventricular hypertrophy.

METHODS

In 348 patients from the Rule Out Myocardial Infarction Using Computer Assisted Tomography trial, 64-slice computed tomography was performed and LVM measured at end-diastole. We used three LVM indexation criteria to obtain three cohorts: LVM indexed to body surface area by echocardiography (n = 337) and computed tomography criteria (n = 325), and by height (n = 326). The cohorts were subdivided into concentric remodeling and normal geometry. Extent of coronary plaque was classified based on a 17-segment model, treated as a continuous variable, and stratified into three groups: zero segment, one to four segments, and more than four segments.

RESULTS

Patients with more than four segments of coronary plaque had higher LVM (Delta12.8-15.1 g) and LVMi (Delta4.0-5.5 g/m and Delta2.2 g/m) than those without CAD (all P < or = 0.03). After multivariable adjustment, LVM and LVMi remained independent predictors of extent of coronary plaque, with 0.27-0.29 segments more plaque per 20 g increase of LVM (all P = 0.02), 0.32-0.34 segments more plaque per 10 g/m increase of LVMi (both P = 0.02), and 0.80 segments more plaque per 10 g/m increase of LVMi (P = 0.008). Concentric remodeling patients had 1.1-1.3 segments more plaque than those with normal geometry (all P < or = 0.05). Patients with more than four segments of plaque had two-fold increase in odds (all P < or = 0.05) of having concentric remodeling as compared with those without CAD.

CONCLUSION

Increased LVM, LVMi, and concentric remodeling are associated with a greater degree of coronary plaque burden in patients without left ventricular hypertrophy. These findings could provide an indication to intensify medical therapy in patients with subclinical CAD and hypertension.

Association of myocardial ischemia and coronary angiographic lesions with increased left atrial dimension during exercise tolerance tests among patients without known coronary heart disease

The association between left atrial (LA) dilation and fundamental exercise parameters has not shared equal extensive investigation as its clinical correlate, interatrial block (IAB; P waves > or =110 ms). We prospectively identified 94 consecutive patients with LA dilation on 2-dimensional transthoracic echocardiography but without atrioventricular valvular disease, hypertension, or coronary artery disease who had undergone coronary angiography after exercise tolerance tests (ETTs) for assessment of new coronary artery disease. Duke prognostic treadmill (DPT) scores were calculated and exercise capacity was expressed as METs of workload achieved. We appraised the cohort for common co-morbidities, IAB on electrocardiography at rest, and exercise-induced P-wave increments (divided into 20-ms quintiles). IAB (67% vs 34%, p = 0.002) and increased LA dimension (48 +/- 6 vs 45 +/- 5 mm, p = 0.01) were associated in patients with >70% coronary artery diameter stenoses and were equally reflected by positive ETT results (79.5% vs 20%, p <0.001), decreased METs (11.43 + [-0.60 x LA size (millimeters)], r(2) = 0.04), and lower DPT scores (35.23 + [-0.70 x LA size (millimeters)], r(2) = 0.73). Incremental P-wave change was associated with lower METs and DPT scores but with positive ETT results and significant coronary artery stenoses (p for trend <0.001). LA dimension was largest in the highest quintile (>60 ms) of P-wave change (p for trend <0.001). In conclusion, increased LA dimension is significantly associated with myocardial ischemia during ETT and is reflected by lower METs and DPT scores and a higher incidence of coronary artery diameter stenoses >70% in patients matched by age-, gender-, and LA size without preexisting coronary artery disease.

Left ventricular hypertrophy, subclinical atherosclerosis, and inflammation

To elucidate mechanisms by which left ventricular (LV) hypertrophy (LVH) increases the risk of atherosclerotic heart disease, we sought to determine whether LVH is independently associated with coronary artery calcium (CAC) and serum C-reactive protein (CRP) levels in the general population. The Dallas Heart Study is a population-based sample in which 2633 individuals underwent cardiac MRI to measure LV structure, electron beam CT to measure CAC, and measurement of plasma CRP. We used univariate and multivariable analyses to determine whether LV mass and markers of concentric LV hypertrophy or dilation were associated with CAC and CRP. Increasing quartiles of LV mass indexed to fat-free mass, LV wall thickness, and concentricity, but not LV volume, were associated with CAC in both men and women (P<0.001). After adjustment for traditional cardiovascular risk factors and statin use, LV wall thickness and concentricity remained associated with CAC in linear regression (P<0.001 for each). These associations were particularly robust in blacks. LV wall thickness and concentricity were also associated with elevated CRP levels (P=0.001 for both) in gender-stratified univariate analyses, although these associations did not persist in multivariable analysis. In conclusion, concentric LVH is an independent risk factor for subclinical atherosclerosis. LVH is also associated with an inflammatory state as reflected in elevated CRP levels, although this relationship appears to be mediated by comorbid conditions. These data likely explain in part why individuals with LVH are at increased risk for myocardial infarction.

Racial differences in the association of coronary calcified plaque with left ventricular hypertrophy: the National Heart, Lung, and Blood Institute Family Heart Study and Hypertension Genetic Epidemiology Network

Studies have reported a lower burden of calcified atherosclerotic plaque in coronary arteries in African-Americans than in whites. Findings from autopsy studies of sudden cardiac death have suggested a link between left ventricular hypertrophy and severity of coronary atherosclerosis. Echocardiograms and cardiac computed tomograms were analyzed in 334 African-American (84% hypertensive) and 196 white (66% hypertensive) adults with no history of coronary heart disease or revascularization procedures at study entry. The relation of coronary artery calcium (CAC) score to left ventricular mass and left ventricular mass indexed to body surface area was assessed by Spearman's correlations and mixed linear models. Covariates included age, gender, field center, weight, height, systolic blood pressure, number of antihypertensive medications, diabetes, total and high-density lipoprotein cholesterol levels, and current smoking and alcohol consumption. In African-Americans, a significant and independent association between CAC score and left ventricular mass or left ventricular mass indexed to body surface area was present with the 2 analytic strategies. Spearman's correlation coefficients for CAC score with left ventricular mass and left ventricular mass indexed to body surface area were 0.14 (p = 0.015) and 0.13 (p = 0.025), respectively, after multivariable adjustment. In whites, the associations of CAC score with measurements of left ventricular mass were weaker and only marginally significant in mixed linear models. In conclusion, these findings suggest that CAC reflects a different risk burden between African-Americans and whites, and future studies examining the prognostic implications of CAC in African-Americans should consider the potential association between CAC and left ventricular hypertrophy.